EP2867554B1

EP2867554B1 - Material processing device with slip clutch and method for implementing a slip clutch in a material-processing device

Info

Publication number: EP2867554B1
Application number: EP13809248.1A
Authority: EP
Inventors: Shmuel REZNIK
Original assignee: Individual
Current assignee: Epd Technology Ltd Co No 515800589
Priority date: 2012-06-27
Filing date: 2013-06-23
Publication date: 2023-03-15
Anticipated expiration: 2033-06-23
Also published as: US9744659B2; ES2946471T3; PT2867554T; PL2867554T3; IL220671A; DK2867554T3; IN2015MN00108A; WO2014002084A1; EP2867554A1; EP2867554A4; US20150118008A1; IL220671A0

Description

Technical Field

The embodiments of the invention relate to a substantially circular material-processing tool having a slip clutch integrally mounted and embedded therein to form an enhanced material-processing device to which rotation is provided by a power tool.
The invention relates to a device according to the preamble of claim 1 and a method according to the preamble of claim 3.

Background Art

Rotary material processing machines, and in particular handheld power tools, for example for grinding and cutting, using fiber abrasive discs, or diamond on steel discs, or other available discs, present an operative challenge to operators, or users. Fig. 1 provides an example of an available material-processing tool mounted on a power tool. For the sake of nomenclature and ease of drawing, reference is made in the figures and in the text hereinbelow to a cutting disc, even though the embodiments of the present invention are not limited to such type of material processing tool but encompass processing tools such as discs or wheels or substantially flat tools like circular saws and discs, for cutting, grinding, polishing, and the like.
Fig. 1 illustrates an example of an existing, common standard off-the-shelf processing tool 19, or standard processing tool 19, such as a cutting disk 19 that is clamped by a clamping device or by clamping means 34, such as between the clamping jaws 34, or jaws 34, of a power tool 30, which is not shown in the Figs. The power tool 30 has a spindle 32 on which are mounted a second-side jaw 34s and a first-side jaw 34f. The second-side jaw 34s is proximal to the power tool 30, and the first-side jaw 34f is distal therefrom. The second-side jaw 34s is coupled in rotational engagement with the spindle 32 and is configured to receive the standard material processing tool 19 thereon. The first-side jaw 34f may be supported by a nut, not shown, or be engaged by screw threads on the spindle 32, to close the jaws 34 against each other over the standard processing tool 19. Alternatively, and for the same purpose, the first-side jaw 34f may be configured as another fastening device, not shown in Fig. 1.
The standard off-the-shelf processing tool 19 has a central bore 25 that is centered on a jaw protrusion 35, which is disposed on the second side jaw 34s, and is thus concentric to the spindle 32.
U.S. Patent No. 2,156,047 to A. B. Arnold et al. recites a frictional driving connection for coupling a driving element to a driven element.
U.S. Patent No. 2,167,744 to I. R. Cosby et al. , discloses improvements for saw arbors for rotary or circular saws.
U.S. Patent No. 2,726,524 to P. X. Gorin divulges a saw blade retainer and a kickback clutch assembly.
German Patent No. 1 089 148 to Curt Stoll K. G. , recites an overload slip clutch for circular saws the clutch having springs which are mounted on the exterior of the saw blade, to apply thereto adjustable pressure loads. This document discloses a device as per the preamble of claim 1 and a method as per the preamble of claim 3.
European Patent Application No. EP 1 375 094 A1 to Black and Decker Inc. discloses a rotary blade clamping assembly and a multiple disc slip clutch that is added to the blade clamping assembly which slip clutch is disposed on the exterior of the rotary blade. Slippage occurs between the surfaces of the multiple disc clutch.
US Patent No. 2,572,042 to Charles A. Martin divulges means for mounting cutting blades on shafts by use of clamping disks which exert gripping pressure against opposite sides of the cutting blade. When the movement of the cutting blade is resisted sufficiently to over-come the frictional engagement of the clamping disks, these disks will slip on opposite sides of the cutting blade.
US Patent Application Publication US2011/0179931 A1 to Gregory A. Menze recites a blade mounting assembly wherein the left side face of the blade is clamped to an engagement face while the right side of the blade is in contact with a biasing element which is exterior to the cutting blade.
German Utility Patent No. 1 756 113 to Maschinenfabrik Heinrich Gutberlett recites a device for fixing circular saw blades to a shaft. Between the saw blade and a pressure part there is provided a friction layer material which is loaded against the blade by disk springs or the like.
Japanese Patent Application No. JPH0957701A to Hitachi Koki Haramachi Co. Ltd. divulges an elastic collar which is provided between two flanges of a conventional rotary tool and is retained with the collar. Pressing the collar by use of the flanges expands the collar to the outer periphery.
US patent no. 2,691,180 of February 1949, to Bernard M. Pineless , recites a shoe cover sewing machine, but is silent about a slip clutch that is integrally embedded in the processing tool/disk like tool (10), and about a hub structure.
Since none of the patent cited hereinabove provides a clutch integrally embedded in the processing tool, it would be advantageous to provide such an option.

Summary of Invention

The present invention provides a device according to claim 1.
A preferred embodiment of the present invention provides for the clamps 34 that are clamped on the processing device 60 to redress a loss or a discrepancy of predetermined axial pressure fit.
According to the invention a hub 40 is supporting at least one resilient pressure ring 50P that is disposed coaxially therewith and with the processing tool 20. According to the invention the at least one pressure ring 50P is disposed on one of a first side 22f, a second side 22s, and both sides of the processing tool 20, such that the at least one pressure ring 50P, the hub 40 and the processing tool 20 form a slip clutch 10 integrally embedded in the material processing device.
According to the invention the hub 14 is coaxial with the central opening 20CB of the processing tool 20. Furthermore, the at least one pressure ring 50P is disposed on one of a first side 22f, a second side 22s, and both sides of the processing tool 20. Thereby, the at least one pressure ring 50P, the hub 40 and the processing tool 20 form a slip clutch 10 integrally embedded in the material-processing device.
Preferably, the at least one pressure ring 50P may be coupled in rotational engagement with the hub 40.
According to the invention, the at least one pressure ring 50P is preloaded to apply a predetermined axial pressure fit on the processing tool 20.
Preferably, the hub 14 is configured to support at least one shim ring 50SH.
According to the invention at least one cover ring 50C is fixedly coupled to the hub 40, and the hub 14 supports a couple of cover rings configured to compress the processing tool 20 therebetween.
The present invention provides a method for implementing a slip clutch 10 in an enhanced material-processing device 60 according to claim 3.
According to the invention a clutch mechanism 12 preloads the material processing device 60 in axial compression through a predetermined elastic strain distance Δt to provide a friction fit.
According to the invention the hub 40 is supporting at least one resilient pressure ring 50P disposed in concentricity therewith and with the processing tool 20, where at least one pressure ring 50P is disposed on one of a first side 22f, a second side 22s, and both sides of the processing tool 20. Thereby, the at least one resilient pressure ring 50P, the hub 40 and the processing tool 20 form a slip clutch 10 integrally embedded in the enhanced material-processing device 60.
Preferably, clamps 34 are clamped on the processing device 60 to redress a loss of predetermined axial pressure fit.

Technical Problem

In practice, operators using cutting wheels or discs may encounter difficulties, for example when the angle of attack between the cutting wheel and the cut, or processed material, is altered, and in case the shape of the object and of the material cut by the cutting wheel changes. As a result thereof, there may occur events such as seizure of the processing tool in the processed material, loss of control of the power tool, backslash, and processing tool or work piece breakdown. Such events may even be dangerous and possibly fatal to the operator, and to a lesser degree, may cause overload of the machine, and lead to premature failure of both machine and cutting media. Hence, and especially so for handheld machines, the common approach of providing a rigid power transfer from the machine or power tool 30 to the cutting tool, is far from being ideal.
Therefore, clutches, torque limiters, and various types of overload protection devices mounted into power tools or power machines have been proposed. The limited success encountered by such machine-mounted clutches may be due to the narrow range of compatibility between the one specific clutch, which is dedicated to a particular purpose, versus the versatility of use of different processing tools that may be mounted on the same power tool. One power tool may accommodate many types of material processing cutting or other discs, which are made of various material sizes and shape, rotating in a range of cutting speeds, and operative on different types of workpieces.
It would therefore be advantageous to provide an enhanced material-processing device having a slip clutch integrally incorporated therein. The slip clutch should be simple to produce, and may but marginally add to the cost and to the mass of inertia of the material processing tool. The slip clutch may be calibrated to let the processing tool slip when a specific predetermined torque limit or threshold torque is reached. When slipping starts, power transfer from the spindle 32 to the desired and enhanced material-processing tool should diminish, and the rotational speed of the material-processing tool should slow down relative to the spindle. Slow down may extend over a span of diminishing rotational speeds, whereafter, according to circumstances, full and undiminished power transfer should recover or else, the material-processing tool should stop to rotate.

Solution to Problem

The solution of the problem is achieved by integrally incorporating and embedding a slip clutch 10, having a predetermined torque threshold limit, on a material processing tool 20, which is a slightly modified standard processing tool 19, to form an enhanced material-processing device 60.
As shown in Fig. 1B, not according to the invention, the jaws 34 of the power tool 30, which is not shown, are rotated by the spindle 32, and apply a sufficient axial clamping force perpendicular to the center portion 21 of a rotating processing tool 20 to prevent slippage thereof while in use. The spindle 32 defines an axial direction. The perpendicular clamping force is a normal force, which is applied by the jaws 34, or by an equivalent thereof, on the surface of the processing tool 20, or disc. The clamping force is superior to and exceeds the maximal arresting force or process force encountered by and applied on the processing tool during the actual processing of a workpiece.
In general, slippage of the processing tool 20 may be dependent on the normal force, on the effective radius of the jaws 34, and on the coefficient of friction µ of the jaws on the substantially circular surface of the processing tool. Slippage of the processing tool 20 relative to the spindle 32 may thus be intentionally made to occur, for example, when the counter-torque caused by the forces necessary for processing the material of the workpiece exceed the multiplication of the normal force applied on the processing tool, times the coefficient of friction µ of the jaws 34 on the enhanced material processing device 60, times the effective radius.
For the jaws 34 of a given power tool 30, and for a given processing tool 20, the two parameters, namely the effective radius of the jaws and the coefficient of friction µ have a predetermined value that a user, not shown, may accept as being given. However, the normal force of closure of the jaws 34 on the processing tool may be controlled and become a predetermined parameter. It is the user himself who closes the jaws 34 of the power tool 30 and thereby applies the normal force on the processing tool 20. Evidently, calling on the user to determine and control the normal force that has to be applied on the processing tool 20 is an impractical request.
Radial friction fits, also referred to as radial pressure fits or radial interference fits, are well known with respect to press-fitting of shafts into bearings, or of bearings into their respective housings. Similarly to radial friction fits, the axial pressure of the jaws 34 on the material processing tool 20 may be regarded as an axial interference fit, or pressure fit, or friction fit, where the jaws 34 rotate in concert with the processing tool. The axial pressure fit may be appropriately calibrated to provide a certain degree of interference fit between the jaws 34 and the processing tool. Such degree of interference may be sufficient to permit slip, thus a diminishing and slowing down of rotation, or sometimes full slip, thus no rotation of the processing tool 20 relative to the rotation of the spindle 32. Slip occurs when a predetermined threshold torque or limit torque is reached. Just like radial friction fits, axial friction fits rely on the compressive elastic stress and strain, thus on the modulus of elasticity of the materials of the associated machine parts.
Figs. 1A and 1B depict a schematic partial cross-section of an example not according to the invention of an enhanced material-processing device 60 wherein a circular central opening 20CB houses a basic slip clutch 10. This means that for example, the central bore 25 of a standard off-the-shelf processing tool 19 has been enlarged into a circular central opening 20CB having a predetermined larger diameter, to form a processing tool 20. The difference between the standard processing tool 19 and the material-processing tool 20 is the enlarged central opening 20CB. The enhanced material-processing device 60 is shown in Fig. 1A before clamping of the jaws 34 on the processing tool 20, and in Fig. 1B after clamping thereof and ready for use.
Fig. 1A illustrates an enhanced material-processing device 60 having a processing tool 20 and a hub 40 forming a basic slip clutch 10, as well as the two jaws 34, namely a first-side jaw 34f and a second-side jaw 34s, and a spindle 32. The spindle 32 pertains to a power tool 30, not shown, that rotates the jaws 34. The processing disc 20, or processing tool 20, has a processing tool first side 22f and a processing tool second side 22s that is supported by the second-side jaw 34s, which also supports the hub second side 40s of the hub 40.
The hub may be made out of rigid material and is shown in detail in Fig. 1C. The hub 40 has an interior diameter 40id and an exterior diameter 40od. The interior diameter 40id is larger than the exterior diameter of the spindle 32, which passes therethrough. The exterior diameter 40od is rotatably retained to the processing tool 20 but in slight retention fit. This means that the hub 40 may be introduced and retained into the enlarged central opening 20CB such that rotation will be allowed. The hub 40, which forms the slip clutch 10 is thereby integrally embedded in the processing tool 20. It is noted that the Figs. are not to scale, and so is the pressure fit distance Δt.
Fig. 1B illustrates a disposition where the jaws 34 forcefully clamp the processing tool 20, ready for workpiece processing operation. The jaws 34 are compressed onto the processing tool 20 until arrested by the hub 40. The deformation Δt is a predetermined axial compression and elastic strain deformation, which is calibrated to provide a selected predetermined axial friction fit, or axial interference fit, or axial pressure fit, on the processing tool 20, sufficient for the jaws 34 to rotate the processing tool for workpiece processing operations. The spindle 32 defines the axial direction. A calibrated axial pressure fit means that when the processing tool 20 encounters a predetermined threshold torque, or limit torque, the jaws 34 may allow slippage of rotation of the processing tool 20 relative to the rotating spindle 32, thus at least lowering the speed of the processing tool.
To this end, the hub 40 is provided with a predetermined hub thickness Ht that is configured to arrest the jaws 34 during axial compression in elastic strain deformation of the processing tool 20. The hub 40, the processing tool 20, and the jaws 34 form a clutch mechanism 12. Thereby, there is provided a slip-clutch 10, which is embedded into and integral with the processing tool 20 and forms therewith an enhanced material-processing device 60.
In brief, the jaws 34 may apply an axial compression elastic strain deformation Δt on the processing tool 20 to create an axial pressure fit. The enhanced material-processing device 60 supports a hub 14 that is associated with a clutch mechanism 12 to form a slip clutch 10. The slip clutch 10 may be integrally mounted and embedded in the enhanced material-processing device 60 and be operative by application thereon of an axial compression friction fit. The slip clutch 10 permits slippage of the processing tool 20 relative to the rotating spindle 32. Total arrest of the processing tool 20 may also occur.
For workpiece processing operation, a user, not shown, may clamp a processing tool 20 between the jaws 34, until the processing tool 20 is compressed through the predetermined elastic strain deformation Δt. This means that the jaws 34 are arrested and seated on the calibrated thickness Ht of the hub 40. At that stage, the processing tool 20 is compressed in predetermined and calibrated axial friction, interference fit, or pressure fit, such that the jaws 34 may rotate the processing tool for material processing operations. However, should the processing tool 20 encounter a predetermined threshold torque limit, then the processing tool may slip to a lower rotation speed relative to the rotation speed of the spindle 32 and of the jaws 34, to prevent a mishap to the user, or an overload to the power tool 30, or both. The operation of the slip clutch 10 may reduce the rotation of the processing tool 20, which may slow down and come near to or even to full rotational arrest. However, after slow down, slippage may cease and the processing tool 20 may recover rotational speed and return to accept full power transfer from the spindle 32. This means that the operation of the slip clutch 10 is reversible.
The hub 14 and the processing tool 20 form an enhanced material-processing device 60 that is operative with a power tool 30 having a rotating spindle 32 and jaws 34 between which is compressed the processing tool that may be of substantially circular circumference.
Fig, 1D illustrates a partial cross-section of one of possible alternative examples of a hub 40 made out of a plurality of concentric hub sleeves. For example, Fig. 1D shows two hub sleeves disposed in mutual radial interference fit, namely a first hub sleeve 40A and a second hub sleeve 40B. This means that the hub 14 may be configured as either one unitary piece of material or as a plurality of pieces of material. The exterior diameter 40od of the hub 14 is configured to allow rotation relative to the interior diameter of the central opening 20CB of the processing tool 20, but may be retained therein in slight retention fit. The interior diameter 40id may be configured to allow passage therethrough in free rotational fit, of the spindle 32. The first and the second hub sleeves, respectively 40A and 40B, together with the clamps 34 and the processing tool 20 form the clutch mechanism 12 of the slip clutch 10.
As still another example, shown in Fig. 4C, the hub 40 is made out of more than two concentric hub sleeves.
It is noted that the coefficient of friction µ such as that of the jaws 34 on the enhanced material processing device 60 for example, does not have a discrete value but covers a range of values, and therefore, the threshold torque limit too, does also covers a range of values. The wording "coefficient of friction µ" and "threshold torque limit" refer to a distribution covering a span of values, but are related to in the present description as representing a discrete value, which is true for practical purposes with the embodiments of the present invention.

Advantageous Effects of Invention

The combination of a slip clutch 10 that is integrated and embedded in a processing tool 20 to form an enhanced material-processing device 60 has also surprisingly resulted in a longer lifespan of the processing tool itself. In addition, the enhanced material-processing device 60 practically allows a workpiece processing procedure that is continuous, without interruption of the work: There is no need to restart the power tool 30 or to retrieve a stuck enhanced material-processing device 60 out of the workpiece. Evidently, the lifetime of the slip clutch 10 may be designed to equal or to exceed the lifetime of the processing tool 20.
Furthermore, should there be made available a power tool 30 with a built-in torque limiter, then that torque limiter will have a specific nominal slip value. In contrast thereto, various enhanced material-processing devices 60 may provide a span of slip values: each one enhanced material-processing device 60 may be produced with a different specific slip value, such that a user may select an enhanced material-processing device 60 that is best adapted to the task at hand. Evidently, an enhanced material-processing device 60 allows the use of a less expensive power tool 30, such a one that is not equipped with a torque limiter.
The disposition of a lightweight slip clutch 10 at the very end of the drive train of the power tool 30 minimizes the time of both the braking and the acceleration of the processing tool 20. A power tool 30 with a built-in torque limiter has rotating elements presenting a significant inertia of mass, whereas practically, with the lightweight enhanced material-processing device 60, there is but the inertia of mass of the processing tool 20.
Fast acceleration and short braking time of the enhanced material-processing device 60 are not only safety measures, but also provide better traction, smooth cutting or processing, and a wider ability of selection of the cutting angle of attack to prevent seizure of the processing tool 20 such as seizure due to collapse of the workpiece. Such features are especially important with workpieces made out of non-homogenous material and with workpieces having various thickness and/or irregular shape.
In addition, the avoidance of frequent successive and sudden arrest-shocks on the processing tool 20, sometimes known as "slip-stick" or "jerking", has resulted in reduced tool wear and better control of the processing tool, particularly when hand-held.
Lastly, the simplicity of design of the clutch assembly 10 features easily implemented and straightforward automatic radial assembly of the inexpensive elements of the enhanced material-processing device 60.

Brief Description of Drawings

Non-limiting embodiments of the invention will be described with reference to the following description of exemplary embodiments, in conjunction with the figures. The figures are generally not shown to scale and any measurements are only meant to be exemplary and not necessarily limiting. In the figures, identical structures, elements, or parts that appear in more than one figure are preferably labeled with a same or similar reference sign or number in all the figures in which they appear, in which:

Fig. 1 shows a prior art material processing tool mounted on a power tool,
Figs. 1A and 1B illustrate a basic slip clutch, not according to the invention,
Figs. 1C and 1D depict details of hubs for a slip clutch,
Figs. 2 and 3 illustrate an embodiment 100,
Figs. 4, 4A, 4B, 4C, and 5 to 8 show details of the embodiment 100,
Fig. 6A depicts radial geometric engagement of a ring with the hub,
Figs. 9 and 9A illustrate an embodiment 200,
Figs. 10 to 12 show further embodiments, respectively 300 to 500,
Fig. 16 depict embodiment 800,
Fig. 16A shows a detail of the embodiment 800,
Fig. 21 is an exploded view of an embodiment 1300.

Description of Embodiments

The exemplary embodiments described hereinabove and hereinbelow are applicable to processing tool 20 that may be selected for example not only as cutting tools, such as cutting disks, but also as circular saw blades, or grinding wheels, or lapping, cleaning, or substance administering tools. Likewise, the power tool 30 for use of the embodiments of the present invention may be selected as a hand-held, hand-driven, automatic, or stationary machines made for various tasks, but not shown in the Figs.
For the sake of reference, items are indicated in the description and in the Figs. by reference signs or reference numerals, independently of their emplacement relative to a side of the processing tool 20. Items that are disposed on the side of the processing tool first side 22f may have a reference sign that carries the suffix f while when disposed on the side of the processing tool second side 22s, may have a reference sign that carries the suffix s.
The enhanced material-processing device 60, or processing device 60 for short, may thus be mounted on a power tool 30, which is not shown, having a spindle 32 and a clamping device or clamping means such as two jaws 34 for example. The processing tool 20 may be clamped between the two jaws 34, namely a first-side jaw 34f and a second-side jaw 34s. The spindle 32 imparts rotation to the processing tool 20 via the jaws 34, in a plane perpendicular to the spindle. The axis X of the spindle, shown in Fig. 8, is disposed perpendicular to the processing tool 20 and defines an axial direction.
The exemplary embodiments described hereinbelow illustrate various enhanced material-processing devices 60 having a torque limiter 10, or slip clutch 10, which is integrated and embedded into a slightly modified substantially circular material-processing tool 20. In other words, the substantially circular enhanced-material processing device 60 includes a material-processing tool 20 having therein an integrally embedded slip clutch 10 operating a clutch mechanism 12. The material processing tool 20, or processing tool 20, has a central opening 20CB and two processing tool sides 22, namely a processing tool first side 22f and a processing tool second side 22s. The central opening 20CB is provided with an enlarged interior diameter.
For the sake of ease of description and for clarity of the drawings, reference is made hereinbelow and in the drawings to a processing tool 20 such as a cutting disc that is mounted on a handheld power tool 30.

Embodiment 100

Figs. 2 and 3 show a partial cross-section of an embodiment 100 of an exemplary enhanced material-processing device 60 having a slip clutch 10 integrally embedded therein. The enhanced material-processing device 60 includes a hub 40, and a plurality of rings 50, where the processing tool 20, the hub, and the rings form the clutch mechanism 12. The plurality of rings 50 may be packed in close coaxial abutment in parallel to each other, may be coaxial with the spindle 32, and may be supported by the hub 40, in concentricity with the processing tool 20. The clutch mechanism 12, or at least portions thereof, such as the hub 40, passes through the central opening 20CB of the processing tool 20, as described hereinbelow, and be integrally embedded in the enhanced material-processing device 60.
The slip clutch 10 is implemented by the application of a predetermined level of axial interference fit, or axial pressure fit forces, on the processing tool 20. The axial pressure fit may be selected to be tight enough to permit rotation of the processing tool 20 for workpiece processing, but may be applied such that above a predetermined torque threshold limit, the processing tool will slip relative to the rotating spindle 32.
The predetermined axial pressure fit is provided by use of one or more compressed elastic and resilient pressure rings 50P that preload, thus apply pressure forces on the processing tool 20. This means that the slip clutch 10 uses one or more resilient pressure rings 50P that have a free thickness before assembly, but are axially compressed during final assembly through a precisely determined compression in elastic strain deformation Δt to apply the desired slip to the clutch 10. Actually, a pressure ring 50P may be considered as a compression spring that is axially loaded through the predetermined elastic strain deformation distance Δt, to provide, in response, the desired friction fit force on the processing tool 20.
Practically, the pressure rings 50P may be compressible, but this is not necessarily so with other rings 50 that are a not pressure rings. Alternatively, the compressibility of the other rings 50, e.g. cover rings 50C, friction rings 50F, and further types of rings described hereinbelow, for example jacket rings 50J, hub ring 50H, and combination rings 50K, may also be taken in consideration to achieve the desired predetermined elastic strain deformation distance Δt. A combination ring 50K combines at least two out of the cover rings 50C, pressure rings 50P, and friction rings 50F.
The hub 40 is configured according to the selected compression-fit deformation Δt. To this end, the hub 40 is provided with arresting surfaces 44, or support surfaces 44 that ensure accurate preload when one or more elements of the clutch mechanism 12 are properly seated thereon. Once preloaded as predetermined for providing the desired axial pressure fit on the processing tool 20 and on the ring(s) 50, the hub 14 may be kept in the preloaded state to form the enhanced material-processing device 60.
However, the axial compression exerted on the pressure ring(s) 50P during final assembly, or relaxation of the pressure after assembly, may provide but a portion of the desired axial compression. Upon mounting of the processing tool 20 on the power tool 30, the clamping jaws 34 may add the final pressure forces to fully achieve the desired predetermined interference fit deformation Δt.
To obtain a fine-tuned torque limiter, or a slip clutch 10 having a narrow-range threshold slip, a precise axial compression interference fit elastic strain deformation Δt of the pressure rings 50P may be required. In turn, for ease of manufacture, the selected strain deformation Δt for the assembly of an embodiment may be provided as the distance separating the flat seating surfaces 44 that are disposed on the hub 40, as shown in Fig. 4. The distance that separates apart the flat seating surfaces 44 is referred to as the distance Ht.
As depicted in Figs. 2 and 3, the hub 40 is disposed concentrically in and through the central opening 20CB of the processing tool 20, and may protrude out of and away from both sides 22 thereof, or at least out and away from one of both sides of the processing tool. The hub 40, also shown in one configuration in Fig. 4, has a hub central opening 40CB defining a hub interior diameter 40id wherethrough passes the spindle 32, which has a smaller exterior diameter, and has an exterior diameter 40od. The hub exterior surface 47 delimits the exterior diameter 40od.
As best seen in Fig. 4, two step-like peripherally circular recesses form parallel circular hub flats 44, namely a first-side circular flat 44f and a second-side circular flat 44s, that are disposed in planes parallel and concentric to, respectively, the first side 22f and to the second side 22s of the processing tool 20. The distance separating both circular flats 44 apart from each other defines the hub thickness Ht, which is associated with the compression fit Δt. Two circular hub protrusions 46, namely a first-side hub protrusion 46f and a second-side hub protrusion 46s, delimit the respective circular flats 44 and prevent their extension up to the hub central opening 40CB. The two circular hub protrusions 46 have a hub protrusion exterior diameter 46od and a hub protrusion interior diameter 40id, which is the diameter of the hub central opening 40CB. The total height of the hub 40 is indicated as HH.
For ease of production, the hub 40 may be implemented out of an assembly of parts. For example, the hub 40 may be assembled out of two or more concentric sleeves, as shown in Figs. 4B and 4C. In Fig. 4B, the hub is made out of two concentrically and firmly mutually attached sleeves 40C and 40D. The sleeve 40C implements the protrusions 46 and is therefore longer than and interior to the sleeve 40D forming the flats 44. As another optional embodiment, the hub may be made out of a plurality of sleeves, as depicted for example with three sleeves in Fig. 4C. In Fig. 4C, the hub 40 is made as shown in Fig. 4B, but the sleeve 40D is divided into two concentrically hub sleeves, namely hub sleeves 40E and 40F. It is the central hub sleeve 40E, intermediate hub sleeve 40C and hub sleeve 40F, that may be configured to form the flats 44. The hub sleeve 40F is disposed in radial interference fit or radial compression fit in the central opening 20CB to allow slip when the threshold torque limit is exceeded.
The hub thickness Ht of the central sleeve 40E is a calibrated and well-defined distance, which is selected to provide the desired axial pressure fit on the processing tool 20 and on the ring(s) 50 during assembly.
The plurality of rings 50 may include various types of rings, at least one resilient pressure ring 50P and a couple of cover rings 50C, further for example, friction rings 50F, jacket rings 50J, pressure and friction rings 50PF, shim rings 50SH, and hub rings 50H. The hub rings 50H may be considered as a type of rings 50, or may be regarded as being a portion of the hub 40. Rings 50 that are disposed on the side of the processing tool first side 22f have a reference sign that carries the suffix f while rings disposed on the side of the processing tool second side 22s have a reference sign that carries the suffix s. In the case of a pressure ring 50P for example, a pressure ring 50Pf and a pressure ring SOPs are disposed, respectively, on the side of the processing tool first side 22f and on the side of the processing tool second side 22s. Likewise, for cover rings 50C, cover rings 50Cf and 50Cs are disposed, respectively, on the side of the processing tool first side 22f and on the side of the processing tool second side 22s. The terms "first side" and "second side" refer, respectively, to the first side 22f and to the second side 22s of the processing tool 20.
For more than one ring 50 of the same type on the same side of the processing tool 20, an integer may be appended to the reference sign. Such an integer may range from 1 to n, where the ring indicated with the digit 1 is disposed closest to the processing tool 20. For example, pressure ring 50Pf3 may designate a third pressure ring disposed on the side of the processing tool first side 22f in addition to two other pressure rings 50Pf, namely 50Pf1 and 50Pf2, where 50Pf1 is closest to the processing tool 20. Since rings 50 of the same type may have a same or different thickness, an integer may be appended to the reference sign t, which is added to the designation of the ring 50. Such an integer may range from 1 to m, where the ring thickness indicated with the digit 1 being disposed closest to the processing tool 20, similar to the description hereinabove with reference to the plurality of rings 50 of the same type.
Figs. 4 to 7 illustrate further details of the exemplary embodiment 100, and Fig. 8 is an exploded view of the processing device 60 shown in Figs. 2 and 3.
Fig. 3 depicts two pressure rings 50P, namely 50Pf and 50Ps that are disposed concentrically around the exterior diameter 40od of the hub 40. One first-side pressure ring 50Pf is disposed on the side of the processing tool first side 22f and one second-side pressure ring 50Ps disposed on the on the side of the processing tool second side 22s. The interior diameter 50Pid of a pressure ring 50P, shown in Fig. 5, may be larger than the exterior diameter 40od of the hub 40, to provide free radial rotation fit about the hub. As described hereinbelow, it is possible to couple a pressure ring 50P having an interior diameter 50Pid in fixed attachment to the hub 40, for example by radial interference fit with the exterior diameter 40od. The thickness of a compressed pressure ring 50P is indicated as Pt. As shown in Fig. 5, a pressure ring 50P has an interior periphery 57, or 57P, and a free thickness or height Pt0 that may be compressed to the thickness or height Pt.
The pressure rings 50P are chosen as elastic and resilient elements, made for example out of rubber, or of elastomeric material, or out of metal, such as an elastic washer or as a mechanical spring. Washers may include for example flat washers, tooth lock washers that are either flat or conical, conical washers, and spring washers. A flat or other metal washer may be made out of Nitinol, or of a super-elastic alloy, or out of shape memory alloy, or of other suitable alloys. As described hereinbelow, pressure rings 50P may also operate as friction rings 50F and as coverings 50C. Pressure rings 50P may be appropriately selected to resiliently apply axial expansion force in response to axial compression forces exerted thereon. Furthermore, pressure rings 50P may be fixedly retained to the processing tool 20 or to the hub 40, or to a ring 50. A pressure ring 50P may be fixedly attached to the processing tool 20, for example by adhesive, or by heat treatment process, or by mechanical means. As shown for example in Fig. 9, more than one pressure ring 50P may be disposed on one side 22 of the processing tool 20. For example, the clutch mechanism 12 may be configured to accept a plurality of first-side pressure rings 50Pf, which are disposed on the side of the processing tool first side 20, and are marked as 50Pf1, 50Pf2, ... , 50Pfn, as shown in Fig. 9 by Pf1 and Pf2. When axially compressed by force away from their free height Pt0, the pressure rings 50P may respond by applying the same force in the opposite direction.
In Fig. 3 there are shown for example, two friction rings 50F that are disposed concentrically around the exterior diameter 40od of the hub 40, one friction ring on each one of the two sides of the processing tool 22. Each one of the two friction rings 50F is disposed in concentric abutment with a respective one of the two pressure rings 50P. The friction rings 50F may be selected as metal rings such as steel or iron washers for example, but other materials may also be considered, such as plastics or artificial materials. The interior diameter 50Fid of a friction rings 50F, shown in Fig. 6, may be larger than the exterior diameter 40od to provide free radial rotation fit about the hub 40. As described hereinbelow, it is possible to implement a friction ring 50F having an interior diameter 50Fid which is fixedly attached to the hub 40, for example by radial pressure interference fit with the exterior diameter 40od. In general, a ring 50 may be disposed in free radial and rotational fit respective to a hub 40, or in radial force friction fit with the hub for fixed retention thereto.
Alternatively, a ring 50, such as the friction ring 50F for example, may be coupled by radial mechanical engagement or radial geometric engagement, for fixed rotational engagement with the hub 40 while allowing axial displacement relative to the axis of rotation X, shown in Fig. 8, or axis of symmetry of the hub. One example of radial geometric engagement of a ring 50 with the hub 40 is shown in Fig. 6A, but evidently, many other variations of radial geometric engagement shapes and means are possible, as well known in the art.
Fig. 6A shows four axial indentations 41 distributed on the exterior surface 47 of the hub 40 and configured to match four ring teeth 51 disposed on the interior periphery 57 of a ring 50. A ring 50 with ring teeth 51 will thus be coupled in radial rotational engagement with a hub 40 having matching indentations 41. However, a ring 50 without ring teeth 51, as show for example in Figs. 5 to 7, may be disposed in free rotational fit relative to a hub 40, even when the hub 40 has axial indentations 41.
A friction ring 50F has a height or thickness that is indicated as Ft, and an interior periphery 57, or 57F.
Cover rings 50C are disposed concentrically around the exterior diameter 46od of the hub protrusions 46, and a cover ring may concentrically abut on one respective friction ring 50F, or other ring 50, that is disposed on one or both sides of the processing tool 20. The interior periphery 57C of a cover rings 50C, shown in Fig. 7, may be fixedly attached to the hub exterior surface 47, for example by radial pressure fit with the exterior diameter 46od of the hub protrusion 46. Alternatively, the interior diameter 50Cid of a cover rings 50C may be larger than the exterior diameter 46od of the hub protrusion 46 to allow free radial rotation fit about the hub 40, but still be fixedly attached to the hub by other means. At least one cover ring 50C is fixedly coupled to the hub 40. Each one of the cover rings 50C covers, at least partially, one circular flat 44 of the hub 40, and may also cover also a respective friction ring 50F, or other ring 50. Ct indicates the height or thickness of a cover ring 50C, as shown in Fig. 7.
When the rings 50 are piled up as in Fig. 3, there is formed a stack or a set of rings 50ST that are disposed in symmetry on each side of the processing tool 20, but asymmetric sets 50ST may also be practical. Closest to the processing tool 20 is the pressure ring 50P, which is followed by the friction ring 50F whereafter comes the cover ring 50C, which is thus the farthest away from the processing tool 20.
One side of the pressure rings 50P may be fixedly attached, say by adhesive, to the processing tool 20 and the other side thereof may be fixedly attached to the respective adjacent friction ring 50F. The cover rings 50C may be fixedly retained to the hub 40, either by radial pressure fit to their respective protrusions 46, or by fixed attachment to their respective circular flats 44. Radial pressure fit means appropriately selected coupling between the internal diameter 50Cid of the cover ring 50C and the external diameter 46od of the hub 40. The attachment of a cover ring 50C to a circular flat 44 may be achieved for example, by use of adhesive, welding and the like, or by mechanical fastening means.
It is noted that if for some reason the axial pressure exerted by and between the cover rings 50C does not precisely provide the desired predetermined axial compression fit elastic strain deformation Δt, the jaws 34 will supplement the missing portion of the deformation when clamping on the processing device 60. This means that the desired axial elastic deformation Δt will be maintained even if some compression force was lost either due to relaxation, flexibility, and deflection of the cover rings 50C, or due to manufacturing inaccuracy.
As described hereinbelow with respect to a set 50ST of the embodiment 100, the processing tool 20, the pressure ring 50P and the friction ring 50F may be attached to each other by adhesive, and the cover ring 50 C may best be fixedly attached to the hub 40. Thereby, when the processing device 60 operates in rotation, and when the predetermined torque limit is reached, the friction rings 50F may slip relative to their respective cover rings 50C. Slipping of the processing device 60 means uncoupling of rotation such that relative to the spindle 32, the processing tool 20 rotates slower, and may sometimes even come to a stop.

Assembly of Embodiment 100

The embodiment 100 of the processing device 60 shown in Fig. 3 may be assembled axially as follows, or in different steps of assembly if so chosen.
To begin with, a second-side cover ring 50Cs may be fixedly attached to the hub 40, as described hereinabove, either by radial compression fit on the second-side protrusions 46s, or by fixed attachment to the second-side circular hub flat 44s. Attachment of the second-side cover ring 50Cs to the second-side circular hub flat 44s may be realized by mechanical fastening, or by use of a welding, or brazing, or soldering process. The second-side cover ring 50Cs may serve as a support for the subsequent rings 50 and for the processing tool 20. Alternatively, not according to the invention, the hub 40 may be configured such that the second-side cover ring 50Cs is built-in as a flange 601 that is an integral portion of the hub, as shown in Fig. 4A for example. Even though the second-side cover ring 50Cs in Fig. 4A is a flange 601 of the hub 40, reference may be made thereto as the second-side cover ring 50Cs. If desired, the hub 40 may be selected as an assembly of concentric hub sleeves 40C and 40D shown in Fig. 4B, or as concentric hub sleeves 40C, 40E, and 40F, shown in Figs. 4C. It is noted that the well-defined hub thickness Ht remains accurately calibrated in the various embodiments of the hub 40 described herein.
Next, a second-side friction ring 50Fs may be centered on the hub 40 and be seated and supported by the second-side cover ring 50Cs, or flange 601. Following that, the second-side pressure ring SOPs may be centered on the hub 40 and be seated on the second-side friction ring 50Fs. If desired, the second-side pressure ring SOPs may be fixedly attached to the second-side friction ring 50Fs, by use of an adhesive for example.
In turn, the processing tool 20 may be centered on the hub 40 and if desired, the second side 22s of the processing tool may be fixedly attached to the second-side pressure ring SOPs, possibly by use of adhesive or other means. For example, the second-side pressure ring SOPs may have a coat of adhesive on both sides thereof and adhere to the second-side friction ring 50Fs on one side, and to the processing tool second side 22s on the other side. Alternatively, the second-side pressure ring SOPs may be chosen as a two-sided adhesive tape, where the material intermediate the adhesive forms the elastic and resilient second-side pressure ring. For example, a two sided adhesive tape may be selected as a double-face polypropylene tape Plasto P573, such as made by Plasto, of 44 de Longvic street, P.O.Box 160, 21304 Chenove Cedex, in France. Other double-face adhesive tapes may also be selected.
Optionally, a pressure ring 50P may be configured as a ring of latex that may be glued to one or to two adjacent rings 50. If desired, a pressure ring may be selected as an O-Ring, the name of which is a Trademark.
So far, the set of rings 50 that is disposed on the second side 22s of the processing tool 20 is stacked and topped by the processing tool 20. In the embodiment 100, the set of rings 50ST that is disposed on both sides of the processing tool 20 is assembled in mutual mirroring symmetry. Hence, the first-side set of rings 50STf that has to be disposed adjacent the processing tool first side 22f, may be disposed in mirroring symmetry to the second-side set of rings 50STs that is already assembled on the second side 22s.
Sequentially, the first-side pressure ring 50Pf may be centered on the hub 40, followed by the first-side friction ring 50Ff and the first-side cover ring 50Cf. The first-side pressure ring 50Pf may be fixedly retained in the same manner as described hereinabove with respect to the second-side set of rings 50STs.
At this stage, the first-side cover ring 50Cf may protrude higher up above the hub thickness Ht and may not be seated on the first-side circular flat 44f, since the pressure rings 50P have not yet been compressed to their loaded or operational thickness Pt.
In the final step of assembly of the embodiment 100 of the processing device 60, the first-side cover ring 50Cf is axially compressed toward the second-side cover ring 50s, such that the rings 50 therebetween are compressed toward the processing tool 20. Under the pressure of axial compression, the two pressure rings 50P will deform or deflect away from their free thickness Pt0 and reach a selected compressed operational thickness Pt.
When the first-side cover ring 50Cf is properly seated on the first-side circular flat 44f, then the shortest distance separating apart between both cover rings 50C is the hub thickness Ht. Thereby, the slip clutch 10 is appropriately compressed to the selected axial pressure fit Δt, and the resilient pressure rings 50P are correctly compressed and both parallel to the processing tool 20. The first-side cover ring 50Cf may now be fixedly attached to the hub 40 to axially support the rings 50 in their compressed state, in the ready-to-operate mode. The fixed attachment of the first-side cover ring 50Cf to the hub 40 may be achieved by radial friction fit with the protrusion 46f, or by fixed attachment to the circular flats 44, as described hereinabove, or by cold forming processes, such as swaging for example.
The result of the assembly process is an enhanced material-processing device 60, or processing device 60, having a slip-clutch 10 that is integrally embedded into the processing tool 20.
In other words, when the first-side cover ring 50Cf, thus the last cover ring to complete the assembly of the slip clutch 10, is fixedly coupled to the hub 40, the pressure rings 50P, which maintain the compression on the processing tool 20, are preloaded under axial loading forces applied thereto. The resultant axial reaction forces applied by the pressure rings 50P onto the processing tool 20 may be equal the assembly loading forces. In operation, the axial force exerted by the jaws 34 on the processing device 60 provide a moment necessary for transfer of rotation from the spindle 32, via the clamps 34, to the processing device 60, to rotate the processing tool 20, but up to a certain torque limit. The torque limit is the threshold torque limit, or slippage threshold that when reached, starts to reduce the speed of rotation of the processing tool 20 relative to the speed of rotation of the spindle 32.
In practice, after assembly of the processing device 60, there may be some relaxation of the pressure exerted by the pressure rings 50 on the processing tool 20. As described hereinabove, the clamping of the jaws 34 on the center portion 21 of the processing tool 20 is directed to firmly seat the cover rings 50C on their respective circular hub flats 44 to return the axial compression fit to the predetermined elastic strain deformation Δt.

Operation of the slip clutch

Within the processing device 60, which is clamped between the jaws 34, the two resilient pressure rings 50P supported by the processing tool 20 force each one of the two friction rings 50F against one of the two respective cover rings 50C. When the jaws 34 rotate the cover rings 50C, rotation may be imparted sequentially therefrom to the friction rings 50F and to the pressure rings 50P that rotate the processing tool 20.
However, the processing tool 20, which may be used for example to cut a pipe made of metal, may become stuck or arrested during the cutting process. This means that the arresting moment encountered by the processing tool 20 is equal to or is greater than the rotational moment exerted by the power tool 30. To prevent damage, either to the power tool 30 or to the processing tool 20, it may be advantageous to disconnect the direct transmission of rotation between the spindle 32 and the processing tool 20. It is the slip-clutch 10 that provides such disconnection of transmission of direct rotational input, which is followed by a limited transfer of rotation sufficient to permit the operator to redirect the processing tool 20 in the workpiece.
The task of the slip-clutch 10 is to limit or to eventually disconnect the rotational input of rotation to the processing tool 20 when this last one is hindered from rotation, thus prevented or even arrested from rotating freely for some reason. When the moment that prevents rotation of the processing tool 20 equals or exceeds a predetermined torque threshold, for which the slip-clutch 10 is designed, slippage will occur. In the embodiment 100, the rings 50 and the processing tool 20 may be disposed in free rotational fit relative to the hub 40. Furthermore, the friction rings 50F may be fixedly coupled to the processing tool 20 via the pressure rings 50C, to form one entity therewith. Likewise, the cover rings 50C are fixedly coupled to the hub 40. In that case, slip will occur on a friction surface FRSR common to a friction ring 50F and a cover ring 50C, as shown in Fig. 2.
The predetermined threshold limit of transmission of rotation of the slip-clutch 10 may be controlled by at least one of the following: the axial force exerted by the pressure rings 50P, the hub thickness Ht, and the coefficient of friction µ, in particular between the friction rings 50F and the cover rings 50C. Evidently, the coefficient of friction µ depends on the material and on the surface treatment of the friction surfaces FRSR. Reference to the friction surfaces is provided hereinbelow.
After seating the cover rings 50C on their respective circular hub flats 44, the compression force exerted by the cover rings 50C depends on the hub thickness Ht of the hub 40. Taking the thickness t of the various rings 50 and the thickness 20t of the processing tool 20 into consideration, it is thus the appropriate selection and mutual adaptation of the hub thickness Ht and of the material wherefrom the rings 50 are made that may determine the predetermined threshold limit of slip of the clutch 10.
Therefore, the hub thickness Ht, which determines the axial compression elastic strain deformation Δt, is one of the parameters, or arguments, defining the controllable torque threshold limit, or slippage threshold of the slip clutch 10. The coefficient of elasticity c of the pressure rings 50P is another one of the parameters, or arguments, defining the controllable torque threshold. It is the axial elastic strain deformation of a pressure ring 50P times the coefficient of elasticity c thereof that creates a resultant axial force. Without taking the jaws 34 into consideration, other parameters may include the coefficient of friction µ of the mutual slipping surfaces and the number of active mutually slipping surfaces, as well as the exterior diameter of the various rings 50.
It is understood from the description hereinabove that various parameters and mechanisms are available with the embodiments of the present invention to control the amount of torque transferred from the rotating spindle 32 to the material processing tool 20.

Operation of the Enhanced Material-Processing Device

An operator, or user, not shown in the Figs., may use the processing device 60 as follows.
First, the processing device 60, which includes the processing tool 20 wherein the slip-clutch 10 is integrally embedded, is clamped between the jaws 34 of the power tool 30. The jaws 34 thereby firmly grip the cover rings 50C. When the power tool 30 is turned to the operative ON state, the rotation of the spindle 32 rotates the jaws 34 whereby the processing device 60 is also rotated. Operation proceeds as with a commonly available power-tool-mounted standard processing tool 19.
The processing device 60, which may be used for example to cut a pipe made of metal, may become stuck during the cutting process. This means that the force encountered at the periphery of the processing tool 20 times the radius thereof is equal to or greater than the moment exerted thereon by the power tool 30. In contrast with a commonly available standard power-tool-mounted processing tool 19, the operation of the slip-clutch of the processing device 60 will prevent damage, to the power tool 30 and/or to the enhanced processing tool 20, by partial or even complete disconnection of rotation of the processing tool. More important, the slip clutch 10 may be selected to prevent loss of
control that the user has over the handheld power tool 30, thus to ensure safe user-control of the power tool. This means that the slip-clutch 10 may partially or completely uncouple the rotation of the processing device 60 relative to the rotation of the spindle 32.
When such an event occurs, the operator may slightly disengage the processing tool 20 out of the cut and then resume the cutting process. Such disengagement mostly calls for a slight retrieval or a change of angle of attack of the processing tool 20, without completely stopping the rotation thereof, to relieve the force hindering the full rotational power transfer from the spindle 32 to the processing tool. Thereafter, the material processing operation proceeds as usual.

Alternative Embodiments

Embodiment

200

Fig. 9 illustrates a schematic partial cross-section of an exemplary embodiment 200 of the processing device 60. In the embodiment 200, a hub 14 is coupled to a recessed processing tool 201 having a central portion 202 and a peripheral portion 203 that are mutually coupled to each other by a cup-like portion 204.
As shown in Fig. 9A, the central circular opening 20CB, which is opened in the recessed processing tool 201, is disposed in a first plane 205 proximal the power tool 30, which is not shown. Furthermore, the peripheral portion 203 is disposed in a second plane 206, which is parallel to and is disposed farther and distally away from the power tool 30 than the first plane 205.
In Fig. 9, the hub thickness Ht protrudes in asymmetry relative to the processing tool 201, much more to the second side 201s than to the first side 201f, but the hub 40 does not cross the second plane 206. If desired however, the hub 40 may be appropriately disposed to protrude in symmetry out of the two sides 202f and 202s of the recessed processing tool 201.
The number of the various types of rings 50 disposed on the second side 201f may be larger than the number of rings disposed on the first side 201s. This means that the number of rings 50 disposed on each side of the recessed processing tool 201 may be the same or may be different. Furthermore, the thickness t of the various types of rings 50 may also be the equal or different. Moreover, the hub 40 may protrude in symmetry or asymmetrically out of the sides of the processing tool 201, which is also true for the various embodiments described in the embodiments of the present invention.
With reference to the embodiment 200 shown in Figs. 9 and 9A, the second-side set of rings 50STs that is disposed on the second side 202s of the central portion 202 of the processing tool 201 includes one cover ring 50Cs, two friction rings 50Fs, and two pressure rings 50Ps. The two second-side friction rings 50Fs are marked as the first second-side friction ring 50Fs1 and as the second second-side friction ring 50Fs2, and the two pressure rings SOPs are indicated as the first second-side pressure ring 50Ps1 and as the second second-side pressure ring 50Ps2.
Likewise, the first-side set of rings 50STf which is disposed on the first side 202f of the central portion 202 may have one cover ring 50Cf, followed in sequential succession by one friction ring 50Ff, and one pressure ring 50Pf.
At least one of the cover rings 50C of the various embodiments of the present invention is fixedly coupled in engagement with the hub 40.
In the same manner as where applicable for the various embodiments of the present invention, the pressure rings 50P may be selected for example as double sided adhesive tape, Belleville springs "crown" type rings, flat washers made of metal or other appropriate materials as in Fig. 5, "wavy" spring washers, and other resilient elements.
In the embodiment 200, like for the other embodiments of the present invention, the processing tool 201 may be disposed in free rotation fit relative to the hub 40, but other types of rings 50 may be coupled in free rotation fit, or in fixed coupling, or in rotational engagement but axially-free coupling, relative to the hub 40. Moreover, selected rings 50 may be coupled either to the processing tool 201 or to other adjacent one or more rings. It is thereby possible to control the number of mutual friction surfaces between rings 50 to obtain a desired torque threshold limit. Further control over the torque threshold limit may be obtained by appropriate selection of the type of material, of the texture of the surface, and of the surface treatment applied to the various rings 50.
With the embodiment 200, the assembly of the rings 50 and of the processing tool 201 on the hub 40 permits to controllably adjust a desired predetermined threshold torque or torque limit of transmission of rotation of the slip-clutch 10, like for the other embodiments described herein. It is noted that it is possible to configure the hub 40 to support a variety of pressure rings 50P and of friction ring 50F in addition to the cover rings 50C.
The axial assembly of the embodiment 200, and the operation and use thereof are similar to the description provided hereinabove respective to the embodiment 100, and is therefore not repeated.

Embodiment 300

Fig. 10 depicts a schematic partial cross-section of an exemplary embodiment 300 showing a hub 14 supporting various types of rings 50.
In Fig. 10, the first-side set of rings 50STf disposed on the first side 22f of the processing tool 20 includes one first-side cover ring 50Cf, one first-side friction ring 50Ff, and one first-side pressure ring 50Pf. The second-side group of rings 50STs disposed on the second side 22s of the processing tool 20 includes the same number and same type of rings 50 as those on the first side 22f, but disposed in mirroring symmetry relative to the processing tool 20.
In the embodiment 300, like for the other embodiments of the present invention, the processing tool 20 may be disposed in free rotation fit relative to the hub 40, but other types of rings 50 may be coupled in free rotation fit, or in fixed coupling, or in rotational engagement but axially-free coupling, relative to the hub 40. Moreover, rings 50 may be mutually coupled either to the processing tool 20 or to each other in couples of two or more of rings. It is thereby possible to control the number of mutual friction surfaces to obtain a desired torque threshold limit.
In comparison with Fig. 3, the order of the pressure rings 50P and of the friction rings 50F has been interchanged.
With the embodiment 300, the assembly of rings 50 and of the processing tool 20 on the hub 40, permits to controllably adjust a desired predetermined threshold torque or torque limit of transmission of rotation of the slip-clutch 10. It is noted that it is possible to configure the hub 40 to support a variety of types of pressure rings 50P and of friction ring 50F in addition to the cover rings 50C.
The axial assembly of the embodiment 300, and the operation and use thereof are similar to the description provided hereinabove respective to the embodiment 100, and is therefore not repeated.

Embodiment 400

Fig. 11 presents a schematic partial cross-section of one more exemplary embodiment 400 similar to the embodiment 100 but with a hub 14 supporting an asymmetric and different arrangement of set of rings 50ST.
In Fig. 11, the first-side set of rings 50STf, which is disposed on the first side 22f of the processing tool 20, includes one cover ring 50Cf, two friction rings 50Ff1 and 50Ff2, and one pressure ring 50Pf. The one pressure ring 50Pf is disposed intermediate between the two friction rings 50Ff2 and 50Ff1. The first first-side friction ring 50Ff1 is disposed adjacent the first side 22f of the processing tool 20, and the second first-side friction ring 50Ff2 is disposed adjacent the first-side cover ring 50Cf most distal relative to the processing tool 20.
The second-side set of rings 50STs that is disposed on the second side 22s of the processing tool 20 includes one cover ring 50Cs, and one friction ring 50Fs. The one second side friction ring 50Fs is disposed intermediate the processing tool 20 and the second side cover ring 50Cs to provide at least one out of two friction surfaces FRSR: For example, one friction surface relative to the processing tool 20 as 50FRSR1, and a second friction surface 50FRSR2 relative the second-side cover ring 50Cs. If desired, an appropriate fixed coupling of the second side friction ring 50Fs to the processing tool 20, say by adhesive, will provide a second friction surface FRSR2 relative the second-side cover ring 50Cs. Similarly, fixed coupling of the second side friction ring 50Fs to the cover ring 50Cs, say by adhesive, or to the hub 40, e.g. by pressure fit interference, will provide a first friction surface FRSR1.
In the embodiment 400, like for the other embodiments of the present invention, the processing tool 20 may be disposed in free rotation fit relative to the hub 40, but other types of rings 50 may be coupled in free rotation fit, or in fixed coupling, or in rotational engagement but axially-free coupling, relative to the hub 40. Moreover, rings 50 may be mutually coupled either to the processing tool 20 or to each other in couples of two or more of rings. It is thereby possible to control the number of mutual friction surfaces FRSR to obtain a desired torque threshold limit.
The cover rings 50C are fixedly attached to the hub either by pressure fit to the protrusions 46, or by fixed retention to the circular hub flats 44, as described hereinabove with respect to the embodiment 100.
With the first side set of rings 50STf, the pressure ring 50Pf may be fixedly attached to the first first-side friction ring 50Ff1 and/or to the second first-side friction ring 50Ff2. If desired, but not shown as such in Fig. 11, the first first-side friction ring 50Ff1 may be fixedly coupled to the processing tool 20 or to the hub 40, and the second first-side friction ring 50Ff2 may be fixedly coupled to the first side cover ring 50Cf or to the hub 40. The various types of ring coupling may provide control over the number of pressure surfaces PRSR. Such couplings may provide at least three friction surfaces FRSR, not shown in Fig. 11, in the first side set of rings 50STf: between the first first-side friction ring 50Ff1 and the processing tool first-side 22f, between the first-side friction ring 50Ff1 and the first side pressure ring 50Pf, and between the first-side second friction ring 50Ff2 and the first-side cover ring 50Cf.
With the first side set of rings 50STf, it is possible to provide one or two friction surfaces FRSR. For two friction surfaces FRSR, one may fixedly attach the first-side first friction ring 50Ff1 to the processing tool 20 and the second first-side second friction ring 50Ff2 to the cover ring 50Cf. Friction will thereby occur on both sides of the first-side pressure ring 50Pf. To obtain but one friction surface FRSR in the first side set of rings 50STf, one may for example fixedly and mutually couple to each other, the first first-side friction ring 50Ff1, the second first-side friction ring 50Ff2, and the pressure ring 50Pf to the processing tool 20. Such coupling will provide one friction surface FRSR1, not shown, between the second friction ring 50Ff2 and the first-side cover ring 50Cf.
Even though not shown in Fig. 11, both sets of rings 50ST may include other combinations of types of rings 50, and a variety of combinations of disposition in sequential order of different types of rings. Furthermore, the number of rings 50 and their type may be selected as desired to obtain a desired predetermined threshold torque limit of the slip-clutch assembly 10.
With the embodiment 400, the appropriate assembly, and selected coupling together of rings 50 and of the processing tool 20 on and with the hub 40, permits to controllably adjust a desired predetermined threshold torque or torque limit of transmission of rotation of the slip-clutch 10. It is noted that it is possible to configure the hub 40 to support a variety of pressure rings 50P and of friction ring 50F in addition to the cover rings 50C.
The axial assembly of the embodiment 400, and the operation and use thereof are similar to the description provided hereinabove respective to the embodiment 100, and is therefore not repeated.

Embodiment 500

Fig. 12 illustrates a schematic partial cross-section of still one more exemplary embodiment 500 similar to the embodiment 400 but with a hub 14 supporting two sets of rings 50ST disposed in mirroring symmetry on both sides 22 of the processing tool 20.
In the embodiment 500, the rings 50 on the first-side set of rings 50STf are identical to the rings on the first-side set of rings 50STf of the embodiment 400. The rings 50 on the first-side set of rings 50STf are also identical to the rings on the second-side set of rings 50STs.
The first-side set of rings 50STf has a pressure ring 50Pf disposed between two friction rings, respectively 50Ff1 and 50Ff2, and these three rings 50 are sandwiched between the processing tool 20 and the first-side cover ring 50Cf.
The description provided hereinabove with reference to the embodiment 400 is also valid for the embodiment 500, and is therefore not repeated.
The first side cover ring 50Cf is fixedly attached to the hub 40 either by pressure fit or by other means as described herein. The same may be true for the second side cover ring 50Cs, which may also be selected as a flange 601 that is integral with the hub 40.
In the embodiment 500, the processing tool 20 is disposed in free rotation fit about the hub 40 and in both the first side and the second side set of rings 50ST, the two friction rings 50F may be coupled in free rotation fit relative to the hub. In addition, the first friction ring 50F1 may be fixedly coupled to the processing tool 20 and the second friction ring 50F2 may be fixedly coupled to the cover ring 50C. Moreover, the pressure ring 50P may be fixedly coupled, or disposed in rotational engagement but axial-free coupling, relative the hub 40. Such attachment will result in each set 50ST of two friction surfaces FRSR, not shown, namely one friction surface FRSR1 between the first friction ring 50F1 and the processing tool 20, and a second friction surface FRSR2 between the second friction ring 50F2 and the cover ring 50C.
Alternatively, other combinations of mutual coupling between rings 50, or attachment of rings to the hub 40 may be selected as desired to result in more or in less friction surfaces FRSR. For example, rings 50 may be mutually attached to each other by adhesive, and rings may be coupled in fixed fit, or in rotational fit, or in rotational engagement but axially-free coupling, relative to the hub 40, by mechanical fastening means or other means known to the art or as described hereinabove.
It is noted that a cover ring 50C may operate simultaneously as a friction ring 50F and/or as a pressure ring 50P.
In the second-side set of rings 50STs, the mutual attachment of rings 50s and their coupling to the hub 40 may be the same or be different from the disposition in the first-side set of rings 50STf.
Even though not shown in Fig. 12, both sets of rings 50ST may include other combinations of types of rings 50, other dispositions of sequential order of rings, and various combinations of mutual attachment and of coupling to the hub 40. The number of rings 50 and their type, or absence and disposition may be selected as desired to obtain a selected predetermined threshold torque limit of the slip-clutch 10. Such arrangements and disposition of the rings 50 permit to controllably adjust a desired predetermined threshold torque limit of transmission of rotation of the slip-clutch 10.
The axial assembly of the embodiment 500 is similar to the assembly of the embodiment 100 and is therefore not repeated.

Embodiment 800

Fig. 16 depicts a partial cross-section of an additional exemplary embodiment 800 having a hub 14 and jacket rings 50J, where a first-side jacket ring 50Jf is disposed on the processing tool first side 22f and a second-side jacket ring 50Js is disposed on the processing tool second-side 22s.
Fig. 16A depicts a jacket ring 50J having a jacket ring interior diameter 50Jid, which is smaller than the interior diameter of the central opening 20CB of the processing tool 20. The central portion 603 of the jacket ring 50J has an interior edge 605 that enters into the central opening 20CB and is bent over a portion of the thickness 20t of the processing tool 20. The central portion 603 of the first side jacket ring 50Jf and of the second side jacket ring 50Js may join each other, completely or partially, at a mutual circular meeting edge 604 formed by meeting of their interior edge 605 in the interior of the central bore opening 20CB. Care is taken for the jacket rings 50J to remain in free rotational fit relative to the hub 40.
The jacket ring 50J may be mechanically coupled to the processing tool 20, say by adhesive or by mechanical fastening means for example. It is possible to use mechanical jacket fasteners 45, such as screws, or pins, or rivets for example, to fixedly couple between the jacket ring 50J and the processing tool 20. Such a mechanical jacket fastener 45 may be introduced perpendicular into the jacket ring 50J and into the processing tool 20. Other mechanical jacket fastener means may include cold fastening techniques, or fastening by mutual embossment of material.
A jacket ring 50J may operate as a friction ring 50F, which provides protection to the processing tool 20. If desired, the two jacket rings 50J may be coupled together at their interior edge 605 for example, by welding, brazing, or soldering together at the meeting edge 604. A jacket ring 50J may be considered as being an integral portion of the processing tool 20.
In Fig. 16, two sets of rings 50ST are disposed in mirroring symmetry on both sides 22 of the processing tool 20. A first-side set of rings 50STf is disposed on the processing tool first-side 22f, and a second-side set of rings 50STs is disposed on the processing tool second side 22s. The sets of rings 50ST are the same as those described hereinabove with respect to the embodiment 300, but are disposed on and in addition to the jacket rings 50J. Therefore, further description is not provided.
Assembly of the embodiment 800 is similar to the axial assembly procedures described hereinabove in relation to the embodiment 100.
Operation and use of the embodiment 800 are alike the description hereinabove referring to the embodiment 300.

Features of the Embodiments

The features illustrated hereinabove for one specific embodiment may be used interchangeably and in combination with other described embodiments when appropriate, within the scope of claims 1 and 3.
The embodiments described hereinabove refer to an enhanced material-processing device 60 including a processing tool 20 of substantially circular circumference operative with a power tool 30 having a rotating spindle 32, and a clamping device, or clamping means, such as clamps 34, for coupling the processing tool 20 to the spindle. The processing tool 20 has an enlarged central opening 20CB entered concentrically therein for receiving at least a portion of the hub 14. In turn, the hub is coupled to the processing tool 20 to form a slip clutch 10 integrally embedded therein, where the slip clutch is configured to slip relative to the rotating spindle 32 when the processing tool reaches a threshold torque limit.
The slip clutch 10 includes a clutch mechanism 12 that is preloaded in predetermined axial compression elastic strain deformation Δt, and is configured to apply a selected axial interference pressure fit on the processing tool 20.
The hub 14 may be configured as at least one sleeve, or as one unitary piece of material or as an assembly made of a plurality of machine parts, and is coaxial with the central opening 20CB of the processing tool 20.
At least one pressure ring 50P is disposed on the first side 22f, or on the second side 22s, or on both sides of the processing tool 20. In such a manner, the at least one pressure ring 50P, the hub 14 the processing tool 20, and the clamps 34, form a slip clutch 10 integrally embedded in the processing tool.
The slip clutch 10 may include one or more rings 50 that may be selected from a group of rings including cover rings 50C, pressure rings 50P, friction rings 50F, jacket rings 50J, hub rings 50H, 50SH and rings 50K forming combination rings, and the ring(s) 50 is/are concentric to the hub 40 and to the spindle 32, and are disposed on a first side 22f, or on a second side 22s, or on both sides of the processing tool 20. The rings 50 may be configured as an annulus, or washer having an interior circular opening concentric with an exterior circular circumference. Alternatively, the rings 50 may be configured as an axisymmetric ring with protrusions departing from a circular periphery, such as teeth for examples. Such teeth, say may protrude radially toward the center of the interior diameter of the ring 50, and/or radially outward and away from the exterior circumference of the ring. Moreover, a ring 50 is not necessarily flat, but a circular protrusion extending axially thereout may determine a radius of contact with an adjacent ring 50 or with the processing tool 20. It is noted that the axial direction is defined by the axis of the spindle 32, which axis is perpendicular to the rings 50 and to the processing tool 20.
A plurality of, or one pressure ring 50P may be fixedly coupled to the hub 40, or be engaged therewith in rotational coupling but in free axial displacement, or be coupled to the processing tool 20, and/or to one or more a ring(s) 50 out of the group of rings and be preloaded to maintain a predetermined axial pressure on the processing tool 20. The clamping jaws 34 of the power tool 30 clamp the processing device 60 in axial compression and redress lacking, lost, or missing predetermined axial pressure fit on the processing tool 20 departing from the desired axial elastic strain deformation Δt.
The at least one pressure ring 50P may be loaded in predetermined axial compression to apply an axial interference pressure fit on the processing tool.
At least one cover ring 50C is fixedly coupled to the hub 14, which may support either a cover ring that is also operative as a pressure ring 50P, or a couple of cover rings configured to compress the processing tool 20 therebetween.
An enhanced processing device 60 operative with a power tool 30 having a rotating spindle 32 that retains and rotates a processing tool 20 of substantially circular circumference, where a central opening 20CB is entered concentrically in the processing tool. Furthermore, a hub 14 is configured to be disposed in the central opening 20CB and coupled to the processing tool 20 in integral embedment therein.
The enhanced material-processing device 60 may have a hub 14 that is configured to support at least one ring 50, which is disposed in concentricity therewith and with the processing tool 20. The at least one ring 50 may be selected alone and in combination out of cover rings 50C, pressure rings 50P, friction rings 50F, jacket rings 50J, hub rings 50H, and combination rings 50K. Furthermore, the at least one ring 50 may be disposed on a first side 22f, or on a second side 22s, or on both sides of the processing tool 20.
Features of the various embodiments described hereinabove may be combined when appropriate. For example, the radial geometric engagement of a ring 50 with the hub 40 as shown in Fig. 6A, may be implemented with friction rings 50F, and is not restricted to the embodiment 100.
The shim rings 50SH are another example of an adjustment ring operative for different embodiments described hereinabove. Furthermore, and also applicable with the various embodiments described hereinabove, the torque limit threshold is controllable and pre-adjustable according to requirements.
Fig. 21 is an exploded view of an embodiment 1300 showing two sets of rings: a first-side set of rings 50STf and a second-side set of rings 50STs aligned with an axis X of the spindle 32, which is not shown. The first-side set of rings 50STf includes a shim ring 50SH that is disposed on the side of the processing tool first side 22f. The first-side set of rings 50STf has a first-side cover ring 50Cf, which is disposed on a first-side pressure ring 50Pf that is supported by a shim ring 50SH covering a first-side friction ring 50Ff. The first-side friction ring 50Ff abuts the processing tool first side 22f. The hub 40, described hereinabove with respect to Fig. 6A, is configured to radially engage the first-side friction ring 50Ff for rotation therewith, but to permit axial displacement of the first-side friction ring. The second-side set of rings 50STs has a second-side friction ring 50s disposed proximal to the processing tool 20 and a second-side cover ring 50s disposed distally away from the processing tool.
A method is described hereinabove for implementing a slip clutch 10 integrally embedded in a material-processing processing device 60 including a processing tool 20 of substantially circular circumference operating with a power tool 30 having a rotating spindle 32. The method comprises providing a concentric central opening 20CB in the processing tool 20 for receiving therein at least a portion of a clutch mechanism 12, and for forming the clutch mechanism by providing a hub 14 disposed at least in portion in the central opening and applying a predetermined axial compression friction fit on the processing tool 20. The method further comprises allowing the processing tool 20 to slip relative to the rotating spindle 32 when a torque limit threshold is reached.
The method further comprises providing at least one ring 50 selected alone and in combination out of rings including cover rings 50C, pressure rings 50P, friction rings 50F, jacket rings 50J, hub rings 50H, shim rings 50SH, and combination rings 50K.
Furthermore, the method comprises disposing the at least one ring 50 in concentricity to the hub 40 on a first side 22f, on a second side 22s, or on both sides of the processing tool 20.
The enhanced material-processing device 60 is configured for repeated use but is a disposable device, to be thrown away, after use, together with the slip clutch 10 that is integrally embedded therein.
The enhanced material-processing device 60 is configured as a readily exchangeable replacement for a standard existing processing tool 19 to be mounted by the user in the same manner as on an available power tool 30 and to clamped between the jaws 34 thereof.

Industrial Applicability

The embodiments described hereinabove are configured for use in industries operating power tools to which substantially circular or wheel shaped tools are used, and for use by manufactures of processing tools 20. The device and the method described hereinabove are applicable to the tool-producing industry and may be used for material processing purposes with hand-held rotating tools as well as with stationary rotating tools.

Reference Signs List

Δt: axial elastic strain deformation
f: first side
c: coefficient of elasticity
s: second side
FRSR: friction surface
Ht: hub thickness
HH: total exterior height of hub of hub rings 50H
X: axis of the spindle 32
10: slip-clutch
12: clutch mechanism
14: hub
19: standard off-the-shelf processing tool
20: material processing tool
20t: processing tool thickness
20CB: central opening
21: center portion of processing tool
22: processing tool side
22f processing tool first side
22s processing tool second side

25: central bore
30: power tool
32: spindle
34: jaws
34f first-side jaw
34s second-side jaw

35: jaw protrusion
40: hub 40
40f first side of hub
40s second side of hub
40id hub interior diameter
40od hub exterior diameter

40A: first hub sleeve
40B: second hub sleeve
40C: hub sleeve
40D: hub sleeve
40E: central hub sleeve
40F: hub sleeve
40CB: hub central opening
41: axial hub indentation
44: circular hub flats
44f first-side circular flat
44s second-side circular flat

45: mechanical jacket fastener
46: hub protrusions
46f first-side hub protrusion
46s second-side hub protrusion
46od protrusions exterior diameter

47: hub exterior surface
48: swaged hub coupling
48f first-side swaged hub coupling
48s second-side swaged hub coupling

50: ring
50C: cover ring
50Cf first-side cover ring
50Cs second-side cover ring
Ct cover ring thickness

50CF: combined cover and friction ring
50CP: combined cover and pressure ring
50CPf first-side combined cover and pressure ring
50CPs second-side cover and pressure ring

50CPF: combined cover, pressure, and friction ring
50F: friction ring
50Ff first-side friction ring
50Fs second-side friction ring
50 Fid
50 Fod
Ft friction ring thickness

50H: hub ring
50Hf first-side hub ring
50Hs second-side hub ring

50HCB: hub ring central bore
50J: jacket rings
50Jf first-side jacket ring
50Js first-side jacket ring

50K: combination ring
50P: pressure ring
50Pf first-side pressure ring
50Ps second-side pressure ring
50Pid interior diameter of pressure ring
50Pod exterior diameter of pressure ring
Pt pressure ring thickness

50SH: shim ring
50ST: set of rings 50
50STf first-side set of rings
50STs second-side set of rings

51: ring tooth
57: ring interior periphery
60: enhanced material-processing device
100 - 1200: embodiments
201: recessed processing tool
201f recessed processing tool first side
201s recessed processing tool second side

202: central portion of 201
203: peripheral portion of 201
204: cup-like portion of 201
205: first plane
206: second plane
601: flange integral with the hub
601od: external diameter of 601

Claims

An enhanced material-processing device (60) including a processing tool (20) of substantially circular circumference, and a power tool having a rotating spindle (32), and clamps (34) for clamping the material processing device (60) therebetween, the enhanced material-processing device (60) further comprising:
a central opening (20CB) entered concentrically in the processing tool (20) for receiving a hub (14, 40),

the hub (14, 40) is coaxial with the central opening (20CB) of the processing tool (20), and the hub (14, 40) being coupled to the processing tool (20),

the hub (14, 40) is supporting at least one resilient pressure ring (50P) disposed coaxially therewith and with the processing tool (20),

the at least one resilient pressure ring (50P) is disposed on one of a first side (22f), a second side (22s), and both sides of the processing tool (20),

the hub (14, 40) is supporting a couple of cover rings (50C) configured to compress the processing tool (20) therebetween, wherein at least one cover ring (50C) is fixedly coupled to the hub (40), said hub (14, 40) having circular hub flats (44),

wherein the clamps (34) firmly grip the cover rings (50C) for firmly seating the cover rings (50C) on their respective circular hub flats (44),

wherein the at least one resilient pressure ring (50P), the hub (14, 40) and the processing tool (20) form a slip clutch (10) configured to allow the processing tool (20) to slip relative to the rotating spindle (32) when a threshold torque limit is reached,

wherein the slip clutch (10) is preloaded in predetermined axial compression elastic strain distance Δt and the at least one resilient pressure ring (50P) is preloaded to apply a predetermined axial pressure fit on the processing tool (20),

characterized in that

the at least one resilient pressure ring (50P), the hub (14, 40) and the processing tool (20) form a slip clutch (10) integrally embedded in the material-processing device (60).
The enhanced material-processing device of claim 1, wherein:
the hub (14, 40) is configured to support at least one shim ring (50SH).
A method for implementing a slip clutch (10) in an enhanced material-processing device (60) including a processing tool (20) of substantially circular circumference, and a power tool having a rotating spindle (32), and clamps (34) for clamping the enhanced material-processing device therebetween, the method comprising the steps of:
providing a concentric central opening (20CB) in the processing tool (20) for receiving a slip clutch (10),

forming the slip clutch (10) by providing a hub (14, 40) disposed in the central opening and applying a predetermined axial compression friction fit on the material processing device (60),

said hub (14, 40) supporting at least one resilient pressure ring (50P) disposed in concentricity therewith and with the processing tool (20), wherein the at least one resilient pressure ring (50P) is disposed on one of a first side (22f), a second side (22s), and both sides of the processing tool (20),

said hub (14, 40) is supporting a couple of cover rings (50C) configured to compress the processing tool (20) therebetween, wherein at least one cover ring (50C) is fixedly coupled to the hub (40),

wherein the at least one resilient pressure ring (50P), the hub (14, 40) and the processing tool (20) form a slip clutch (10) allowing the processing tool (20) to slip relative to the rotating spindle (34) when reaching a threshold torque limit,

wherein a clutch mechanism (12) is provided by preload of the material processing device (60) in axial compression through a predetermined elastic strain distance Δt to provide a friction fit,

wherein said hub (14, 40) has circular hub flats (44),

wherein the clamps (34) firmly grip the cover rings (50C) for firmly seating the cover rings (50C) on their respective circular hub flats (44),

characterized in that

the at least one resilient pressure ring (50P), the hub (14, 40) and the processing tool (20) form a slip clutch (10) integrally embedded in the material-processing device (60).